Resolves #158 - Updates the logback version

[rdifrango]

Resolves elastic/ecs-logging-java#158

Updates the logback version

The details can be found at:

http://slf4j.org/log4shell.html

The key details are these lines:

However, logback may make JNDI calls from within its configuration file. This was recently reported in LOGBACK-1591 as a vulnerability of lesser severity. In response, we have released logback version 1.2.8. Please upgrade.

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#### Build stats * Start Time: 2021-12-17T10:31:17.108+0000 * Duration: 8 min 38 sec * Commit: 17b13402ca904bd7474e6531af6c53258e1b5d18 #### Test stats :test_tube: | Test | Results | | ------------ | :-----------------------------: | | Failed | 0 | | Passed | 171 | | Skipped | 0 | | Total | 171 |

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